Extreme Reliability: Saving With Your Air Compressor System

Making the Best Green $ Decision

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Making the Best Green $ Decision

Fleets have been buffeted by the economic storm for the past several years. Historically, counties and cities have shown recovery from recessions as long as 18-24 months following national economic recovery because of the lag in tax revenue collection associated with an economy in recession. In the US, the National League of Cities has expressed concern that the current downturn will last longer in certain areas since property tax revenues may be reduced longer than anticipated because of depressed property values. In addition, business tax revenues will continue to be weak because many small businesses have failed to weather the crisis, and there are fewer new business startups.

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Pressure to Expand Green Fleet Initiatives

Despite budget constraints, green initiatives continue to gain priority throughout the public works and utility fleet industry. Political support for carbon friendly, low-emission vehicle technologies, along with funding through the federal stimulus package has provided fleets the opportunity to acquire additional green vehicles and equipment.

Support for green fleets is expected to continue despite increasing pressure to reduce costs. Reducing emissions and fuel consumption continue to lead the response to these initiatives. This often means looking at more fuel-efficient tools, equipment and vehicle accessories to add value to this greening effort.

Fleet managers continue struggling to avoid the trap of making the wrong decision for what appears to be the right green choice, and choosing the right air compressor system can be part of this challenge.

Consider the following examples:

• Truck mounted diesel-A 2011, 6L 300-hp diesel work truck uses 50 hp to produce 150 cfm and 0.01 g/hp-hr pm (maximum allowable emissions per EPA regulations); and
• Skid mount diesel drive-A 2011, 10-hp diesel engine uses 10 hp to produce 30 cfm at 0.3 g/hp-hr pm (maximum allowable emissions per EPA regulations).

A job that takes 10 minutes with the truck mounted, 150-cfm air system will produce a total of 0.0833 g/hp-hr, while the same job with the skid mounted 30-cfm compressor can take up to five times as long (50 minutes) and produce a total of 2.499 g/hp-hr. This produces 30 times more, not including additional energy and resources required in the manufacturing process to build, and eventually dispose of, two engines instead of one.

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A smaller, more fuel-efficient system does not necessarily mean green. Cost savings must take into account fuel, labor and the loss of resources (water losses from a broken water main, for example, that can't be promptly repaired when equipment and human resources are tied up at another job).

Condition Extremes

Regardless of location, fleets are expected to operate in freezing climates, intense heat environments and in heavy precipitation-when demand can be greatest. Finding an air compressor that is designed for these conditions can go a long way toward addressing budgetary and environmental concerns.

From fuel and lubrication to equipment readiness to ability to perform to reliability, the design and characteristic of the air compressor a fleet uses can have a direct impact on the organization's biggest concerns.

Some specific air compressor system features can reduce issues that might arise in extreme weather conditions:

Cold Climates

• Specially designed compressor oils, particularly synthetic blends, ensure reliable performance and reduction in equipment issues and maintenance problems.
• Pre-use preparation, such as compressor oil warming to ensure correct viscosity and appropriate hydraulic pressure (cold climate kit or digital control warming stage), also contributes to cost savings and reduced environmental impact.
• Maintaining recommended hydraulic oil viscosity ensures equipment longevity and reduced operating costs.

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Hot Environments

• Air compressors equipped with a variety of system temperature probes ensure hydraulic and compressor fluid temperatures do not exceed recommended limitations by allowing system shutdown with a safety circuit.
• Air-liquid cooling through a dual core cooler with a dedicated electric fan prevents temperature excesses.
• Equipment color and material, such as light colors for reflecting heat and lightweight aluminum panels for superior temperature conduction, keeps equipment in an ideal operating temperature range.

Heavy Precipitation

• Weatherproofed electrical connections ensure uninterrupted operation and reduced maintenance needs.
• O-rings, special weather packs and an air-tight system prevent electrical shorts and potential corrosion.
• All fasteners should be plated or stainless steel; housings should be aluminum, and all other steel items should be fully powder-coated to ensure corrosion-resistance.

Vehicle-mounted Air Compressors and Extreme Weather Conditions

Given the range of services provided by utility fleets and public works, performing in extreme weather conditions-intense heat, severe freezes, dangerous snow events, heavy precipitation and strong winds-is considered mandatory. The public relies on public works and utility fleets for their safety in these extreme conditions. Fleets, therefore, must be able to rely on their vehicles, equipment and tools when these situations arise. Choosing the right vehicle-mounted air compressor can ensure reliability at these times as well as quick response while still addressing budgetary and environmental concerns.

Types of Vehicle-mounted Air Compressors

Most vehicle-mounted air compressors offer a variety of features that allow them to perform in extreme conditions while addressing budgetary concerns and environmental impact. Not all air compressor systems have all the necessary features or are reliable in those circumstances. The types of vehicle-mounted air compressors that can manage these conditions are as follows.

Gas/Diesel Drive

This is a portable or mounted, self-contained compressor system. These compressors can be found skid mounted, chassis mounted or trailer mounted, and are referred to as a tow behind.

• Extreme weather features: may include insulated enclosures, electric battery warmers, oil pan warmers, oversized cooler or block heaters;
• Budget considerations: transferability between vehicles, appropriate-size engines for fuel consumption; and
• Environmental benefits: running a smaller engine reduces exhaust and fuel use.

Power Take-off Direct Drive and Power Take-off Shaft Drive

Both these air compressor systems are driven off a power take-off (PTO) mounted to the vehicle's transmission or split off the vehicle's drive shaft. These typically represent larger, 100 cfm and over compressors.

• Extreme weather features: may include oversized cooler, generally open to the elements;
• Budget considerations: initial install costs are higher, only utilizes the vehicle engine; and
• Environmental benefits: powered by one engine, requires maintenance of one engine, fewer enclosure components (less raw materials used).

PTO Hydraulic Underdeck

This is similar to above deck and PTO direct drive and shaft drive underdecks. The PTO hydraulic is powered by a hydraulic pump driven by the PTO. The difference is that the components are mounted under the vehicle, rather than on top.

• Extreme weather features: may include hydraulic tank heater or an extra hydraulic cooler;
• Budget considerations: initial install costs are higher, only utilizes vehicle engine, less equipment allows for purchase of an additional time, labor and money saving piece of equipment; and
• Environmental benefits: powered by one engine, requires maintenance of one engine, fewer enclosure components (less raw materials used).

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The rotary screw air compressor system is integrated with the truck engine and fully contained under the hood. Compact and powerful, these compressors can produce up to 175 psi and up to 150 cfm.

• Extreme weather features: systems are tied to vehicle cooling system-they automatically benefit from the cooling function in extreme heat conditions and the heating function in extreme cold, mounted under hood they are protected from excess precipitation;
• Budget considerations: uses one engine, reduced weight/payload, decreased idling and emissions, lighter weight construction material, no receiver tank, more compact size reduces required vehicle size, reduced fuel and insurance costs, one less piece of equipment allows for purchase of an additional time, labor and money saving piece of equipment; and
• Environmental benefits: uses one engine, variable speed throttle controls, reduced vehicle weight, improved equipment performance reduces fuel consumption.

Hydraulic Above Deck

This may be a smaller, reciprocating type compressor or a larger, more powerful rotary screw system. It is mounted on the truck deck and usually packaged in a metal enclosure. It's run by hydraulic power, typically from a PTO or sometimes from an engine-driven clutch pump.

• Extreme weather features: may include automatic cold-sensing, pre-warming of hydraulic oil, soft start, cooler bypass check valve;
• Budget considerations: all components needed to run hydraulics, initial cost of bare compressor can be lower, one less piece of equipment allows for purchase of an additional time, labor and money saving piece of equipment; and
• Environmental benefits: throttle-enable functions, soft start, unload and standby modes.

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When making a choice on a vehicle-mounted air compressor system, fleet managers need to take into account their key concerns-tight budgets and environmental impact-as well as the equipment's ability to handle extreme weather conditions. Longevity and reduced maintenance needs contribute toward improved budgets, while proper equipment reduces the environmental impact.

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